Single use syringe for two stroke procedures

ABSTRACT

A single use syringe is provided. The syringe includes features that cause the plunger rod to be locked with respect to the syringe barrel upon completion of a two stroke injection procedure, such as a drug reconstitution and injection sequence. The locking device may include barbs for engaging the syringe barrel and relatively long, proximally extending legs. The legs include barbs for engaging the syringe barrel and end portions for engaging the plunger rod. The plunger rod includes a recess defined by converging surfaces, the recess being displaced from the longitudinal axis thereof. The surfaces of the plunger rod define teeth that are engageable with the locking element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/421,024 filed Oct. 24, 2002 and is also a Continuation-in-Part ofU.S. Application Ser. No. 10/254,924 filed Sep. 25, 2002, which are eachhereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention is related to single use syringes and moreparticularly to auto-disable single use syringes for use in two strokeprocedures.

In the United States and throughout the world, the multiple use ofhypodermic syringe products that are intended for single use only isinstrumental in drug abuse and more particularly in the transfer ofdiseases. Intravenous drug users who routinely share and reuse syringesare a high risk group with respect to the bloodborne pathogens includingHIV and AIDS. Also the effects of multiple use are a major concern inunder-developed countries where repeated use of syringe products may beresponsible for the spread of many diseases. Reuse of single usehypodermic syringe assemblies is instrumental in the spread of drugabuse even in the absence of infection or disease.

Many attempts have been made to remedy this problem, Some of theseattempts have required a specific act to destroy the syringe after useeither by using a destructive device or providing a syringe assemblywith frangible zones so that the syringe could be rendered inoperable byapplication of force. Other attempts have involved the inclusion ofstructure which would allow the destruction or defeating of the syringefunction through a conscious act by the syringe user. Although many ofthese devices work quite well, they do require the specific intent ofthe user followed by the actual act to destroy or render the syringeinoperable.

Other prior art syringes are auto-disable syringes. Such syringesautomatically disable after a single injection stroke is made. Thus,these syringes cannot be used for procedures that require more than asingle aspiration stroke and a single injection stroke. For example,such syringes cannot be used for reconstitution or other applicationswhich require more than a single stroke of the plunger rod.

SUMMARY OF THE INVENTION

The invention relates to a syringe assembly that automatically disablesafter two strokes of the plunger rod. The syringe assembly includes asyringe barrel, a plunger rod having an elongate body portion, astopper, a disc and at least one axially extending recess formed by apair of surfaces radially displaced from the longitudinal axis of saidelongate body portion. The surfaces of the plunger rod define at leastone proximal tooth and at least one distal tooth. A locking element isslidably positioned within the recess and engages the inside surface ofsaid syringe barrel such that said locking element is substantiallyimmovable in the proximal. The locking element is further engageablewith the proximal tooth during said first injection stroke of saidplunger rod and engageable with the distal tooth during said secondinjection stroke of said plunger rod. The locking element engages theteeth of the plunger rod in such a way as to render the syringe assemblyinoperable after completing two strokes of the plunger rod. An annularring is included on the inside barrel of the syringe to limit motion ofthe plunger rod in the proximal direction.

According to another aspect of the invention, the surfaces may define aplurality of proximal teeth and a plurality of distal teeth.

Preferably the locking element is an integral structure comprised of aresilient metallic material but can be formed of any material that isresilient.

According to another embodiment of the invention, a syringe assemblywhich automatically disables after two strokes of the plunger rod isprovided. The syringe assembly includes a barrel, a plunger rodextending including an elongate body portion, a stopper at a distal endof the elongate body portion, a disc, a first axially extending recessformed by a pair of first surfaces radially displaced from thelongitudinal axis of the elongate body portion and a second axiallyextending recess formed by a pair of second surfaces radially displacedfrom the longitudinal axis of the elongate body portion. The first pairof surfaces each define a plurality of teeth and the second pair ofsurface each define at least one proximal tooth and at least one distaltooth. The syringe assembly further includes a locking element slidablypositioned within either of the first or second recesses. According tothis embodiment of the invention, a syringe assembly is provided thatmay be used for procedures requiring only one stroke of the plunger rodor two strokes of the plunger rod. For procedures requiring only onestroke of the plunger rod, the locking element is placed within thefirst recess containing a plurality of teeth. After completion of thesingle injection stroke, the syringe is rendered disabled by the lockingelement. For procedures requiring two injection strokes, the lockingelement is placed within the second recess and the syringe is rendereddisables after two injections strokes are completed.

According to yet another aspect of the invention, a method forperforming a two stroke injection procedure is provided wherein thesyringe is automatically disabled after completion of the secondinjection stroke. The method includes providing a syringe assembly asset forth above, proximally withdrawing the plunger rod until thestopper abuts the annular ring of the barrel while the locking elementremains substantially motionless allowing the proximal tooth to passunder the locking element, distally moving the plunger rod so that thestopper abuts the distal end of the barrel and the proximal tooth abutsthe locking element while the locking element remains substantiallymotionless, proximally withdrawing the plunger rod so that the stopperabuts the annular ring, while the locking element remains substantiallymotionless allowing the distal tooth to pass under the locking elementso that the locking element abuts the distal tooth, distally moving theplunger rod so that the stopper abuts the distal end of the barrel whilethe locking element moves distally with the plunger rod and locking theplunger rod via engagement of the locking element with the barrel andstopper rendering the syringe assembly permanently disabled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, perspective view of a single use syringe assemblyaccording to the invention.

FIG. 2 is a perspective view of the single use syringe assembly of FIG.1 as packaged.

FIG. 3 is a perspective view of the syringe assembly with the plungerrod in position following the first aspiration.

FIG. 4 is a perspective view of the syringe assembly with the plungerrod in position following the first injection.

FIG. 5 is a perspective view of the syringe assembly with the plungerrod in position following the second aspiration.

FIG. 6 is a perspective view of the syringe assembly with the plungerrod in position following the second injection.

FIG. 7 is a cross-sectional view of the syringe assembly as shown inFIG. FIG. 2

FIG. 7A is an exploded cross-sectional view of the syringe assemblyshown in FIG. 7.

FIG. 8 is a cross-sectional view of the syringe assembly as shown inFIG. 3

FIG. 8A is an exploded cross-sectional view of the syringe assembly asshown in FIG. 8.

FIG. 9 is a cross-sectional view of the syringe assembly as shown inFIG. 4.

FIG. 9A is an exploded cross-sectional view of the syringe assembly asshown in FIG. 9.

FIG. 10 is a cross-sectional view of the syringe assembly as shown inFIG. 5.

FIG. 10A is an exploded cross-sectional view of the syringe assembly asshown in FIG. 10.

FIG. 11 is a cross-sectional view of the syringe assembly as shown inFIG. 6.

FIG. 11A is an exploded cross-sectional view of the syringe assembly asshown in FIG. 11.

FIG. 12 is a is a cross section view of the syringe assembly taken alongline 10-10 of FIG. 7.

FIG. 13 is a perspective vie of the plunger rod.

FIG. 14 is a top perspective view of the locking element.

FIG. 15 is a bottom perspective view of the locking element.

FIG. 16 is a side elevation view of the locking element.

FIG. 17 is a cross-sectional view of the locking element taken alongline 16-16 of FIG. 16.

FIG. 18 is a cross-sectional view of the locking element taken alongline 17-17 of FIG. 16.

FIG. 19 is an end view of the locking element.

FIG. 20 is an exploded, perspective view of a single use syringeassembly according to the another embodiment of the invention.

FIG. 21 is a perspective view of the syringe assembly of FIG. 20 aspackaged.

FIG. 22 is a perspective view of the syringe assembly of FIG. 20 withthe plunger rod in position following the first aspiration.

FIG. 23 is a perspective view of the syringe assembly of FIG. 20 withthe plunger rod in position following the first injection.

FIG. 24 is a perspective view of the syringe assembly of FIG. 20 withthe plunger rod in position following the second aspiration.

FIG. 25 is a perspective view of the syringe assembly with the plungerrod in position following the second injection.

DETAILED DESCRIPTION

Referring to FIGS. 1-11A, a single use syringe assembly 20 includes abarrel 22 having an inside surface 24 defining a chamber 26 forretaining fluid. The inside surface 24 of the barrel further defines anannular ring 27 projecting therefrom. The barrel 22 includes an openproximal end 28 and a distal end 30 having a collar 32 defining apassageway 34 therethrough in communication with the chamber. A needlecannula 10 projects outwardly from the distal barrel end and is in fluidcommunication with the chamber 26. The collar 32 of the barrel as shownis a non-standard collar and therefore cannot be used with a standardneedle cannula, e.g., a standard luer locking cannula Therefore, reuseof the needle or the syringe is difficult. It will be appreciated thatthe invention could be applied to syringe assemblies having permanentlyaffixed needles or needle/hub assemblies, or fixed or removable bluntcannulas, or standard luer locking assemblies. While intended forreconstitution of vaccines, the syringe assembly can be used for generalcurative purposes or other purposes.

As used in the preceding paragraph and hereafter, the term “distal end”refers to the end furthest from the person holding the syringe assembly20. The term “proximal end” refers to the end closest to the holder ofthe syringe assembly 20. In the preferred embodiment, the proximal end28 of the barrel 22 includes a flange 36 to facilitate handling andpositioning of the syringe assembly 20 and to maintain the relativeposition of the barrel 22 with respect to a plunger rod 38 duringfilling and medication administration.

The plunger rod 38 used in the syringe assembly 20 includes an elongatebody portion 40 including a plurality of elongate recesses 42 runningsubstantially parallel to the longitudinal axis of rotation thereof. Thedistal end of the elongate body portion 40 includes an integral stopper44. A disc-shaped flange 46 is provided at the proximal end of theplunger rod 38 for allowing the user to apply the force necessary tomove the plunger rod 38 with respect to the barrel 22.

The elongate body portion 40 includes a distal disc 48 and a proximaldisc 50 intermediate to the proximal and distal ends thereof. Thesections between the relatively proximal disc 50 and the flange 46 andthe relatively distal disc 48 and the stopper 44 include radiallyextending walls 51, 52, both of which preferably traverse thelongitudinal axis of rotation of the plunger rod 38. Additional pairs ofdistal walls 53 resembling fins extend perpendicularly from both sidesof one wall 52 of the radially extending walls in the section betweenthe distal disc 48 and stopper 44. In this embodiment, as shown in theFIGS. 1-9, there are four pairs of distal walls 53 including wall faces55, 57. A first pair 53 a of distal walls extend perpendicularly fromthe upper side of wall 52 and a second pair 53 b extend from the lowerside of wall 52. The third and fourth pairs are mirror images of thefirst and second extending from the wall 52 on the side opposite fromthe first and second pairs beyond wall 51.

In a preferred embodiment, each of the distal walls 53 is substantiallyparallel to each other. The areas between each of the pairs of wallscould be filled in to provide additional rigidity if necessary. Teeth 54are formed on selected surfaces of the walls 53. In a preferredembodiment, each of the first pair 53 a of distal walls defines a pairof teeth including a proximal tooth 58 and a distal tooth 59 on wallfaces 55, 57. Each of the second pair 53 b of distal walls defines aplurality of teeth 54 b. The proximal tooth is located adjacent to thedistal disc 48 while the distal tooth 59 is located at some pointbetween the distal disc 48 and the stopper 44. An area 62 having noteeth is defined between the distal tooth 58 and proximal tooth 58. Eachtooth 54, 58, 59 includes a corresponding distally facing surface orshoulder 56. The wall surfaces 55, 57 including the teeth, convergealong an imaginary line that runs substantially parallel to thelongitudinal axis of the plunger rod assembly, but radially displacedtherefrom. As shown in the drawings, the surfaces 55, 57 do notnecessarily adjoin each other. The wall surfaces 55, 57 define recesses42 for positioning of a locking element 60. While four recesses areprovided, a greater or lesser number may be employed. It will beappreciated that the recesses 42 can be formed by surfaces that actuallymeet along the line of convergence. It will further be appreciated thatwhile the plunger rod assembly as shown and described herein is ofintegral construction, it may in fact be comprised of two or moreseparate elements. The stopper 44 may, for example, be a separatecomponent made from a material that is different from the materialcomprising the remainder of the plunger rod assembly. Preferably, thesyringe barrel is comprised of polypropylene, and contains an internallubricant and the plunger rod assembly is comprised of polyethylene.

According to one embodiment of the invention, the diameter of the barrelis that of a standard 10 ml 2 piece syringe, at least about 13.5 mm(0.53 inch). For delivery of smaller doses, for example, 2 ml, 3 ml, 5ml, the length of the syringe is reduced from the length of the standard10 ml syringe to the length required to deliver the smaller dose. Thus,the bulk of the syringe is reduced, while the pressure can be moreeasily controlled due to the greater diameter of the barrel. Fordelivery of larger doses, for example, 10 ml, the diameter of a standard20 ml barrel, or larger barrel, can be used, while, again reducing thelength of the syringe to accommodate the smaller dose. The reduction inthe bulk of the syringe reduces the packaging, which is advantageous insyringes having an integral cannula. The diameter of the plunger is alsoincreased, increasing the pressure it exerts. This improves thereconstitution process.

The locking element 60 is positioned within the barrel 22 and within oneof the elongate recesses 42 defined by the pairs of distal walls 53. Asshown in the drawings, the locking element 60 is placed within the firstpair of walls 53 a which each define distal and proximal teeth 58, 59.When the locking element 60 is placed within either of the first pair ofdistal walls 53 a, the syringe may be used for reconstitutionprocedures, or any other procedure requiring two strokes of the plungersince there are two teeth 58, 59. This operation is set out in moredetail below. Alternatively, the locking element 60 may be placed withinthe second pair of distal walls 53 b, which define a plurality of teeth54. When placed in this location, the plunger is only capable of asingle injection stroke, and therefore, the syringe 20 cannot be usedfor procedures requiring more than one aspiration and injection stroke.This operation is set out in more detail below. The recess 42 acts as apathway for longitudinal motion of the locking element 60 relative tothe plunger rod assembly 38. Since the recesses 42 are displaced fromthe longitudinal axis of the plunger rod assembly 38, the same sizelocking element 60 can be used that is employed in a smaller syringe. Inthe smaller syringe, the locking element would be positioned in a recessadjoining the longitudinal axis or at least closer to this axis than inthe syringe disclosed herein. U.S. Pat. Nos. 4,961,728 and 5,989,219disclose the placement of a locking element at or near the longitudinalaxis. A syringe as disclosed in these patents could be provided foradministering doses of about 0.5 ml. The invention allows the same sizelocking element to be used in a wide range of syringes, such as verysmall syringes (0.5 ml) as well as those exceeding five milliliters (5ml).

The locking element 60, as best shown in FIGS. 12-18, includes agenerally V-shaped body portion 61 comprising first and second radiallyextending walls 62, 64 joined along a longitudinal axis. The walls 62,64 preferably form an angle of greater than ninety degrees, andpreferably about one hundred degrees. A first leg 66 extends proximallyfrom the first wall 62 and a second leg 68 extends proximally from thesecond wall 64. The legs 66,68 flare outwardly with respect to theV-shaped body portion 61, as best shown in FIG. 2. The legs 66, 68 arepreferably substantially longer than the length of the body portion 61.For example, in a locking element having an overall length of aboutseventeen millimeters, the legs 66, 68 may be about ten millimeters inlength.

Each of the legs 66, 68 includes a proximal end portion 70, 72 that isangled towards one of the walls 53 of the plunger rod. They furtherinclude inner and outer edges. (The terms “inner” and “outer” arerelative terms as used herein.) The inner edges thereof aresubstantially adjacent to each other, separated by a longitudinal gap74. Barbs 76, 78 are integral with the outer edges of the first andsecond legs. The barbs face proximally, and are preferably locatedslightly distally of the angled end portions 70, 72. The barbs may bedifferent in appearance from those shown in the drawings so long as theyare capable of engaging the inside surface 24 of the syringe barrel toprevent proximal movement of the locking element 60.

A second pair of legs 80, 82 extends distally from the V-shaped bodyportion 61. One of these legs 80 extends from the first wall 62 and theother 82 from the second wall 64. Barbs 84, 86 extend proximally fromthe distal ends of the legs 80, 82. The barbs 84,86 are formed on theouter edges of the distally extending legs 80,82. Each leg furtherincludes a cutting edge 87 capable of penetrating the stopper 44.

The locking element 60 is preferably formed from a thin sheet of metalsuch as stainless steel. The thickness in a preferred embodiment thereofis about 0.20 mm. The dimensions of the locking element 60 are selectedin accordance with the barrels and plunger rod assemblies with which itis to be used. The angle formed between the two halves of the lockingelement 60, as shown in FIG. 12, is preferably greater than ninetydegrees, and preferably about one hundred degrees. When placed in one ofthe recesses 42 in the plunger rod, the locking element will accordinglyexert a force against the two of the converging wall surfaces 55, 57that define the recess. The cutting edges 87 are preferably formed byproviding bevels on one side of the substrate from which the lockingelement is constructed. It will be appreciated that the substrate couldbe ground on both sides thereof to form cutting edges 87 for disablingthe stopper 44. Other methods for creating cutting edges could also beemployed, such as photochemical machining, which are well known in theart. Alternatively, barbs (not shown) or other cutting members can beprovided on the locking element for piercing the stopper.

The syringe assembly is easily constructed from the component partsthereof and packaged as shown in FIGS. 1 and 2. First, the lockingelement 60 is positioned in one of recesses 42 in the plunger rod suchthat the angled end portions of the legs 66, 68 adjoin the relativelydistal disk 48. As shown in FIGS. 1 and 2, the locking element 60 ispositioned in the recess 42 formed by the first pair of distal walls 53a. In this position, the syringe may be used for a reconstitutionprocess as will be illustrated. The legs 66, 68 and spring member extendproximally, and the barbs 76, 78, 84, 86 are all angled proximally withrespect to the plunger rod 38. The plunger rod/locking element assembly21 is then inserted into the barrel 22 through the proximal end thereof.

As the assembly 21 is moved distally within the barrel, the angularorientation of the barbs allows them to slide along while engaginginside surface 24 of the barrel. The locking element 60 moves distallywith the plunger rod 38 due to the engagement of the ends of legs 66, 68with the disc 48. The gap 74 is maintained between the legs 66, 68 evenafter installation of the locking element. The maintenance of the gapand the relatively long lengths of the legs 66,68, which act ascantilever springs, provide a relatively reduced force on the barrel andfacilitate use and installation. The plunger rod/locking elementassembly 21 is moved distally until the stopper 44 engages an end wall23 of the barrel 22. The annular ring 27 is spaced accordingly in thebarrel 22 so that when the stopper 44 abuts the end wall 23 the proximalends 70,72 of the locking element 60 are approximately at the locationof the distal disc 48. The assembly of the syringe is then complete andthe syringe is ready for use or storage. A needle cover 62 can bemounted to the distal end of the barrel onto the collar 32 to protectthe needle cannula. The cover is removed prior to use.

In use, plunger rod assembly 121 is retracted in the proximal directionfrom the position shown in FIGS. 2, 7 and 7A to the position shown inFIGS. 3, 8 and 8A in order to perform the first aspiration, drawingreconstitution fluid or diluent through needle cannula 10 and passageway34 and into chamber 26 of barrel 22. The plunger is retracted proximallyuntil the stopper 44 abuts the ring 27. Locking element 60 remainssubstantially stationary with respect to barrel 22 during suchretraction, and the plunger rod 38 is moved proximally with respect toboth barrel 22 and the locking element 60. This is due to the engagementof barbs 76, 78, 84, 86 with inside surface 24 of the barrel. The barbsare preferably made from a harder material than the barrel, whichenhances their ability to resist proximal movement. As the plungercontinues to move proximally, angled ends 70, 72 of legs 66, 68 of thelocking element ride 60 over the proximal tooth 58 of the plunger rodduring retraction thereof. The stopper 44 abuts the ring 27 before thelocking element rides over the distal tooth 59 as shown in FIGS. 3, 8and 8A. Thus, the locking element 60 does not pass over the distal tooth59. The teeth 58, 59 are spaced apart to allow the locking element 60 topass over only the proximal tooth 58 during the first aspiration whileallowing the proper quantity of reconstitution fluid to be withdrawninto the syringe 20. For example, about 3.0-3.4 ml of reconstitutionfluid is required for a 3 ml dose. Thus, the locking element 60 and thering 27, which are appropriately spaced to provide the proper quantityof reconstitution fluid into the chamber 26, limit the retraction of theplunger rod 38 during aspiration.

The reconstitution fluid may now be injected from chamber 26 into alyophilized drug container (not shown). During the injection of thereconstitution fluid, the plunger is moved distally until the stopper 44abuts end wall 23. This injection stroke empties the contents of thesyringe into the drug container in order to reconstitute the drug. Thelocking element 60 remains substantially motionless, but may be slightlymoved by the proximal tooth 58 during the injection of thereconstitution fluid into the lyophilized drug container as shown inFIGS. 4, 9 and 9A.

The reconstituted drug in the lyophilized drug container may now bedrawn from the lyophilized drug container into the chamber 26 of thesyringe. During the aspiration of the reconstituted drug, the lockingelement 60 passes over the proximal tooth 59 as shown in FIGS. 5, 10 and10A. The plunger 38 is withdrawn proximally until the stopper 44 abutsthe ring 27. The distal end of the locking element 60 now abuts theproximal side of the stopper 44. The user feels the engagement of boththe locking element 60 and stopper 44 and the annular ring 27 andstopper 44. Cutting edges 87 do not penetrate the stopper 44 as a resultof the forces exerted during normal use. As the locking element 60cannot be moved proximally, further retraction of the plunger rod 38 isresisted. The amount of fluid that can be drawn into chamber 26 isaccordingly limited by the distance between the proximal surface of thestopper 44 and the disc 48 as well as the length of the locking element60 and the location of the ring 27. It will be appreciated that thedistance between the stopper 44 and the relatively distal disc 48, thelength of the locking element 60, the location of the ring 27 and thedistance between the proximal and distal tooth 58, 59 can be chosen tomeet the needs of particular applications. As discussed above, thelocking element 60 is substantially immovable in the proximal directionwithin the barrel due to the engagement of the barbs with the insidesurface of the barrel 22.

Once the reconstituted drug has been drawn into the barrel 22 from thelyophilized drug container, the needle cannula can be removed from thefluid source and used for injection. During the injection of a patient,plunger assembly 38 and locking element 60 both move distally from thepositions shown in FIGS. 10 and 10A to the positions shown in FIGS. 11and 11A. In FIGS. 11 and 11A, stopper 44 again adjoins or engages theend wall 23 of barrel 22. At this point, locking element 60 remainspositioned on the distal side of the distal tooth 54 a and proximal end70 of locking element 60 engages distal shoulder 56 a of distal tooth 54a. Both plunger rod 38 and the locking element 60 are substantiallyimmovable from their positions since barbs 76, 78, 84, 86 are engaged toinside surface 24, which resist proximal movement of plunger 38. Syringeassembly 20 accordingly cannot be reused. Should a person useextraordinary force in an attempt to retract the plunger rod assemblyfrom the position shown in FIGS. 11 and 11A, the cutting edges 87 at thedistal end of the locking element 60 will penetrate the stopper,rendering it unusable. Disabling of the stopper 44 preferably occurswhen the force exerted is approximately sufficient to dislodge thelocking element 60 in the proximal direction, or a lesser force. Asdiscussed above, simple engagement of the cutting edges 87 and stopper44 should not compromise the integrity of the stopper 44.

An additional tamper-resistance feature is comprised of notches 89 inthe plunger rod 38. If the plunger rod 38 is twisted forcefully, it willbreak prior to disablement of locking element 60.

If the locking element 60 is positioned within the recess 42 defined bythe second pair of distal walls 53 b and accordingly teeth 54, thesyringe would only be usable for a single aspiration and injectionstroke. The syringe would operate in the same way as fully disclosed inU.S. patent application Ser. No. 10/254,924 filed Sep. 25, 2002.

Thus, the same plunger assembly 38 can be used for singleaspiration/injection procedures or procedures requiring two aspirationsand injections. Alternatively, the plunger assembly 38 may be providedwith distal walls 43 that each only include a proximal tooth 58 and adistal tooth 59. In such a device, the locking element 60 may be placedin any recess 42 in order to perform a reconstitution procedure.

Referring now to FIGS. 20-25, another embodiment of the invention isillustrated. This embodiment of the invention automatically disables thesyringe after a two stroke procedure is performed, for applications inwhich the volume of the reconstitution fluid or diluent necessary toreconstitute the drug exceeds the volume of the actual dose to bedelivered. For example, 3.2 ml of reconstitution fluid can be used toreconstitute a drug and then the practitioner may choose to deliver 2,3, or 4 ml of drug. The treatment of tuberculosis, for example, requirethe reconstitution of 1 ml of Streptomycin with 3.2 ml of diluent, toform 4 ml of drug at a concentration of 250 mg/ml. The standard dosesare then determined by body ass of the patient, typically 2 ml, 3 ml, or4 ml of drug.

FIG. 20 shows a single use syringe assembly 120 including a barrel 122having an inside surface 124 defining a chamber 126 for retaining fluid.The inside surface 124 of the barrel further defines an annular ring 127projecting therefrom. The barrel 122 includes an open proximal end 128and a distal end 130 having a collar 132 defining a passageway 134therethrough in communication with the chamber. A needle cannula 110projects outwardly from the distal barrel end and is in fluidcommunication with the chamber 126. The needle cannula 110 and thecollar 132 as show in the FIGS. are integral with the barrel. It will beappreciated that the invention could be applied to syringe assemblieshaving permanently removable needles or needle/hub assemblies, or fixedor removable blunt cannulas, or standard luer locking assemblies. Whileintended for reconstitution of vaccines, the syringe assembly can beused for general curative purposes or other purposes.

The proximal end 128 of the barrel 122 includes a flange 136 tofacilitate handling and positioning of the syringe assembly 120 and tomaintain the relative position of the barrel 122 with respect to plungerrod 138 during filling and medication administration.

The plunger rod 138 used in the syringe assembly 120 includes anelongate body portion 140 including a plurality of elongate recesses 142running substantially parallel to the longitudinal axis of rotationthereof. The distal end of the elongate body portion 140 includes anintegral stopper 144. A disc-shaped flange 146 is provided at theproximal end of the plunger rod 138 for allowing the user to apply theforce necessary to move the plunger rod 138 with respect to the barrel122.

The elongate body portion 140 includes a pair of discs 148, 150intermediate to the proximal and distal ends thereof. The sectionsbetween the relatively proximal disc 150 and the flange 146 and therelatively distal disc 148 and the stopper 144 include radiallyextending walls 151, 152, both of which preferably traverse thelongitudinal axis of rotation of the plunger rod 138. Additional pairsof distal walls 153 resembling fins extend perpendicularly from bothsides of one wall 152 of the radially extending walls in the sectionbetween the distal disc 148 and stopper 144. In this embodiment, asshown in the FIGS., there are four pairs of distal walls 153 includingwall faces 155, 157. One pair of distal walls 153 extend perpendicularlyfrom the upper side of wall 152 and another pair extend from the lowerside of wall 152. The third and fourth pairs are mirror images of thefirst and second extending from the wall 152 on the side opposite fromthe first and second pairs beyond wall 151.

In a preferred embodiment, each of the distal walls 153 is substantiallyparallel to each other. The areas between each of the pairs of wallscould be filled in to provide additional rigidity if necessary. Incontrast to the previous embodiment, the embodiment of the inventiondisclosed in FIGS. 20-25 include a plurality of distal teeth 158 and aplurality of proximal teeth 159 rather than just a single proximal tooth58 and a single distal tooth 59. As shown in FIGS. 20-2, there are threeproximal teeth 58 and three distal teeth 59, but the number of proximalteeth and distal teeth may be modified according to the dosage ofmedication necessary. The distal teeth 158 and proximal teeth 159 areformed on selected surfaces of the walls 153. Each of the distal andproximal teeth 158, 159 includes a corresponding distally facing surfaceor shoulder 156. The wall surfaces 155, 157 including the teeth,converge along an imaginary line that runs substantially parallel to thelongitudinal axis of the plunger rod, but radially displaced therefrom.The wall surfaces 155, 157 define recesses 142 for positioning of alocking element 60. While four recesses are provided, a greater orlesser number may be employed. It will be appreciated that the recesses142 can be formed by surfaces that actually meet along the line ofconvergence. It will further be appreciated that while the plunger rodas shown and described herein is of integral construction, it may infact be comprised of two or more separate elements. The stopper 144 may,for example, be a separate component made from a material that isdifferent from the material comprising the remainder of the plunger rod.Preferably, the syringe barrel is comprised of polypropylene, andcontains an internal lubricant and the plunger rod is comprised ofpolyethylene.

According to this embodiment of the invention, the dimensions of thesyringe barrel are that of a standard 10 ml 2 piece syringe. In apreferred embodiment, the length of the plunger rod from the distal disc148 to the stopper is about 55.7 mm; the total length of the proximalteeth is about 16.6 mm and length of area 162 is about 8.0 mm. Theannular ring 127 is located on the inside of the barrel 122 at aposition approximately 33.1 mm from the end wall 135 at the distal end130 of the barrel. These measurements are merely illustrativemeasurements of the preferred embodiment to allow for delivery of a drugtypical in the tuberculosis regimen. For other applications requiring atwo-stroke procedure, the location and lengths of the proximal teeth anddistal teeth, as well as the location of the annular ring 127 can beadjusted accordingly.

The syringe assembly 120 is easily constructed from the component partsthereof and packaged as shown in FIGS. 20 and 21. First, the lockingelement 60 is positioned in one of recesses 142 in the plunger rod 138such that the angled end portions of the legs 66, 68 adjoin therelatively distal disk 48. The legs 66, 68 and spring member extendproximally, and the barbs 76, 78, 84, 86 are all angled proximally withrespect to the plunger rod 38. The plunger rod/locking element assembly121 is then inserted into the barrel 122 through the proximal endthereof.

As the assembly 121 is moved distally within the barrel, the angularorientation of the barbs allows them to slide along while engaginginside surface 124 of the barrel. The locking element 60 moves distallywith the plunger rod 138 due to the engagement of the ends of legs 66,68 with the disc 148. The gap 74 is maintained between the legs 66, 68even after installation of the locking element The maintenance of thegap and the relatively long lengths of the legs 66,68, which act ascantilever springs, provide a relatively reduced force on the barrel andfacilitate use and installation. The plunger rod/locking elementassembly 121 is moved distally until the stopper 144 engages the endwall 135 of the barrel 122 and the distal portion of the locking element60, including the cutting edge 87 and barbs 84 abut the annular ring127. The ring 127 is spaced accordingly in the barrel 122 so that whenthe stopper 44 abuts the end wall 135 the proximal ends 70, 72 of thelocking element 60 are approximately at the location of the distal disc148. The assembly of the syringe is then complete and the syringe isready for use or storage. A needle cover can be mounted to the distalend of the barrel onto the collar 132 to protect the needle cannula. Thecover is removed prior to use.

In use, plunger rod assembly 121 is retracted in the proximal directionfrom the position shown in FIG. 21 to the position shown in FIG. 22 inorder to perform the first aspiration, drawing reconstitution fluid ordiluent through needle cannula 110 and passageway 134 and into chamber126 of barrel 122. The plunger is retracted proximally until the stopper144 abuts the ring 127. Locking element 60 remains substantiallystationary with respect to barrel 122 during such retraction, and theplunger rod 138 is moved proximally with respect to both barrel 122 andthe locking element 60. This is due to the engagement of barbs 76, 78,84, 86 with inside surface 124 of the barrel. The barbs are preferablymade from a harder material than the barrel which enhances their abilityto resist proximal movement. As the plunger continues to moveproximally, angled ends 70, 72 of legs 66, 68 of the locking elementride 60 over all of the plurality of proximal tooth 58 of the plungerrod during retraction thereof. The stopper 144 abuts the ring 127 beforethe locking element rides the plurality of distal teeth 159 as shown inFIG. 22. Thus, the locking element 60 does not pass over any of thedistal teeth 159. The proximal teeth 158 and the distal teeth 159 arespaced apart to allow the locking element 60 to pass over only theproximal teeth 158 during the first aspiration while allowing the properquantity of reconstitution fluid to be withdrawn into the syringe 120.Thus, the locking element 60 and the ring 127, which are appropriatelyspaced to provide the proper quantity of reconstitution fluid into thechamber 126, limit the retraction of the plunger rod 138 duringaspiration.

The reconstitution fluid may now be injected from chamber 126 into alyophilized drug container (not shown). During the injection of thereconstitution fluid, the plunger is moved distally until the stopper144 abuts end wall 135, as shown in FIG. 23. This injection strokeempties the contents of the syringe into the drug container in order toreconstitute the drug. The locking element 60 travels with the plunger138 due to the primal end of the locking element contacting the distalmost proximal tooth 158, as shown in FIG. 23.

The reconstituted drug in the lyophilized drug container may now bedrawn from the lyophilized drug container into the chamber 126 of thesyringe. During the aspiration of the reconstituted drug, the lockingelement 60 passes over the proximal teeth 159 as shown in FIG. 24. Theplunger 138 is withdrawn proximally until the stopper 144 abuts the ring127. The distal end of the locking element 60 now abuts the proximalside of the stopper 144. The user feels the engagement of both thelocking element 60 and stopper 144 and the annular ring 127 and thestopper 144. Cutting edges 87 do not penetrate the stopper 144 as aresult of the forces exerted during normal use. As the locking element60 cannot be moved proximally, further retraction of the plunger rod 138is resisted. The amount of fluid that can be drawn into chamber 126 isaccordingly limited by the distance between the proximal surface of thestopper 144 and the disc 148 as well as the length of the lockingelement 160 and the location of the ring 127. It will be appreciatedthat the distance between the stopper 144 and the distal disc 148, thelength of the locking element 60, the location of the ring 127, thelength of the proximal and distal teeth 158, 159 and the distancebetween the proximal and distal teeth 158, 159 can be chosen to meet theneeds of particular applications.

Once the reconstituted drug has been drawn into the barrel 122 from thelyophilized drug container, the needle cannula can be removed from thefluid source and used for injection. During the injection of a patient,the plunger 138 and the locking element 60 both move distally from theposition shown in FIG. 24 to the position shown in FIG. 25. As shown inFIG. 25, the stopper 44 again adjoins or engages the end wall 135 ofbarrel 122. At this point, locking element 60 remains positioned on thedistal side of the distal teeth 159 and proximal end 70 of lockingelement 60 engages distal shoulder 56 of distal teeth 159. Both plungerrod 138 and the locking element 60 are substantially immovable fromtheir positions since barbs 76, 78, 84, 86 are engaged to inside surface124, which resist proximal movement of plunger 38. Syringe assembly 120accordingly cannot be reused. Should a person use extraordinary force inan attempt to retract the plunger rod assembly from the position shownin FIG. 25, the cutting edges 87 at the distal end of the lockingelement 60 will penetrate the stopper, rendering it unusable. Disablingof the stopper 144 preferably occurs when the force exerted isapproximately sufficient to dislodge the locking element 60 in theproximal direction, or a lesser force. As discussed above, simpleengagement of the cutting edges 87 and stopper 144 should not compromisethe integrity of the stopper 144.

The syringe barrel of the present invention may be constructed of a widevariety of rigid materials with thermoplastic materials such aspolypropylene and polyethylene being preferred. Similarly, thermoplasticmaterials such as polypropylene, polyethylene and polystyrene arepreferred for the plunger rod and integral stopper. A wide variety ofmaterials such as natural rubber, synthetic rubber, thermoplasticelastomers and combinations thereof are suitable for the stopper if thestopper is manufactured as a separate component. The choice of stoppermaterial will depend on compatibility with the medication being used.

As previously recited, it is preferable that the locking element 60 befabricated from a material which is harder than the barrel 22 so thatthe locking barbs may effectively engage the barrel 22. Resilient springlike properties are also desirable along with low cost, dimensionallyconsistent fabrication. With this in mind, sheet metal is the preferredmaterial for the locking element 60 with stainless steel being preferredfor medical applications. Although the locking element of the preferredembodiment is fabricated from a single sheet, it is within the purviewof the instant invention to include locking elements made of other formsand/or containing multiple parts. Locking elements having structuresother than that shown and described herein could also be successfullyemployed. One such locking element is disclosed in U.S. Pat. No.5,989,219, the disclosure of which is incorporated by reference herein.The distal end of the locking element disclosed in the patent could beprovided with a cutting edge similar to those described above.Alternatively, barbs (not shown) could be provided at the distal end ofthe locking element for rendering the stopper unusable.

The syringe barrel employed in accordance with the invention may have avarying wall thickness along its length. The portion of the barrel usedfor containing medication could be relatively thin and resilient toensure proper sealing with the stopper. The remainder of the barrelcould be relatively thick and less resilient such that it would tend tocrack if squeezed by pliers or another device used for attemptedtampering. Sufficient barrel crystallinity is desirable in the area ofthe locking element to cause this area to crack upon deformation of thesyringe barrel to an extent that would permit retraction of the plungerrod with the locking element.

Thus, it can be seen that the present invention provides a simple,reliable, easily fabricated, single use syringe which becomes inoperableor incapable of further use without any additional act on the part ofthe user. It further allows the use of a locking element of the samesize that is used on smaller or larger syringes. It even further allowsuse of a plunger with a variety recesses, which contain teetharrangements to achieve the desired dosage range and plunger retractionsequences.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention.

1. A syringe assembly comprising: a syringe barrel having an insidesurface defining a chamber, an open end, and a distal end; a plunger rodextending within said syringe barrel, said plunger rod including anelongate body portion defining a longitudinal axis, a stopper at adistal end of said elongate body portion, a disc, and at least oneaxially extending recess formed by a pair of surfaces radially displacedfrom the longitudinal axis of said elongate body portion, each of saidsurfaces defining at least one proximal tooth and at least one distaltooth, said plunger rod being substantially immovable after performing afirst retraction stroke in the direction of said open end, a firstinjection stroke in the direction of said distal end, a secondretraction stroke in the direction of said open end and a secondinjection stroke in the direction of said distal end; and a lockingelement slidably positioned within said recess, said locking elementengaging said inside surface of said syringe barrel such that saidlocking element is substantially immovable in the direction of the openend of said syringe barrel, said locking element further beingengageable with said at least one proximal tooth during said firstinjection stroke of said plunger rod and said locking element beingengageable with said at least one distal tooth during said secondinjection stroke of said plunger rod.
 2. The syringe assembly of claim1, wherein said barrel further defines an annular ring for limitingmovement of said plunger rod in the direction of said open end.
 3. Thesyringe assembly of claim 2, wherein said plunger rod movement islimited in the direction of the open end during said first retractionstroke when said stopper abuts a said annular ring.
 4. The syringeassembly of claim 2, wherein said plunger rod movement is limited in thedirection of the open end during said second retraction stroke when saidstopper abuts a said annular ring.
 5. The syringe assembly of claim 1,wherein said at least one proximal tooth comprises a plurality ofproximal teeth and said at least one distal tooth comprises a pluralityof distal teeth.
 6. The syringe assembly of claim 1, wherein said atleast one proximal tooth comprises three teeth.
 7. The syringe assemblyof claim 1, wherein said at least one distal tooth comprises threeteeth.
 8. The syringe assembly of claim 1 wherein said locking elementis comprised of an integral, resilient metal structure, said lockingelement being positioned such that said plunger rod can be movedproximally with respect to said locking element.
 9. The syringe assemblyof claim 1 wherein said locking element includes one or more proximallyextending barbs engaging said inside surface of said syringe barrel, andsaid locking element and stopper are positioned such that said plungerrod can be moved proximally with respect to said locking element. 10.The syringe assembly of claim 9 wherein said locking element includes abody portion having a distal end and proximal end, said body portion ofsaid locking element being generally V-shaped and engageable with eachof said pair of surfaces.
 11. The syringe assembly of claim 10 includinga first pair of legs extending from and deflectable with respect to saidproximal end of said body portion, said legs engaging said plunger rod.12. The syringe assembly of claim 11 including a first proximallyextending barb adjacent said distal end of said body portion and asecond proximally extending barb extending from at least one of saidlegs, said first and second barbs engaging said inside surface of saidsyringe barrel.
 13. The syringe assembly of claim 1 wherein saidelongate body portion of said plunger rod includes a plurality ofradially extending walls that converge near said longitudinal axis and afirst additional wall extending from one of said radially extendingwalls in a non-radial direction, said first additional wall defining oneof said surfaces forming said recess.
 14. The syringe assembly of claim13 including a second additional wall extending from one of saidradially extending walls, said second additional wall defining one ofsaid surfaces forming said recess.
 15. The syringe assembly of claim 14wherein said second additional wall is substantially parallel to saidfirst additional wall.
 16. The syringe assembly of claim 1 wherein saidelongate body portion of said plunger rod includes a first wall proximalto said stopper and a plurality of second walls projecting from a firstside of first wall, two of said second walls defining said surfacesforming said recess.
 17. The syringe assembly of claim 1 wherein saidannular ring is spaced a distance from said distal end such that saiddistance defines a volume of said chamber to be substantially equal to adesired reconstitution dose.
 18. The syringe assembly of claim 17wherein said locking element has a longitudinal length substantiallyequal to said distance.
 19. The syringe assembly of claim 1 furthercomprising a needle cannula attached to said distal end of said barreland in fluid communication with said barrel.
 20. The syringe assembly ofclaim 19, wherein said needle cannula further includes a hub forremovably attaching said needle cannula to said barrel.
 21. The syringeassembly of claim 19, wherein said needle cannula defines a sharpeneddistal tip.
 22. The syringe assembly of claim 19, wherein said needlecannula is permanently attached to said barrel.
 23. The syringe assemblyof claim 19, wherein said needle cannula defines a blunt distal tip. 24.A syringe assembly comprising: a syringe barrel having an inside surfacedefining a chamber, an open end, a distal end and an annular ring, aplunger rod extending within said syringe barrel, said plunger rodincluding an elongate body portion defining a longitudinal axis, astopper at a distal end of said elongate body portion, a disc, a firstaxially extending recess formed by a pair of first surfaces radiallydisplaced from the longitudinal axis of said elongate body portion, eachof said first surfaces defining a plurality of teeth, and a secondaxially extending recess formed by a pair of second surfaces radiallydisplaced from the longitudinal axis of said elongate body portion, eachof said second surfaces defining at least one proximal tooth and atleast one distal tooth; and a locking element slidably positioned withinone of said first or second recesses, said locking element engaging saidinside surface of said syringe barrel such that said locking element issubstantially immovable in the direction of the open end of said syringebarrel, said locking element further being engageable with said teeth.25. A syringe assembly of claim 24, wherein said locking element isslidably positioned within said first recess, said locking elementengaging said inside surface of said syringe barrel such that saidlocking element is substantially immovable in the direction of the openend of said syringe barrel, said locking element further beingengageable with said plurality of teeth such that said plunger rod andlocking element can be moved distally together toward said distal end ofsaid syringe barrel with said locking element being maintained in saidrecess and substantially displaced from the longitudinal axis of saidplunger rod
 26. A syringe assembly according to claim 24, wherein saidlocking element is slidably positioned within said second recess so thatsaid plunger rod is substantially immovable after performing a firstretraction stroke in the direction of said open end, a first injectionstroke in the direction of said distal end, a second retraction strokein the direction of said open end and a second injection stroke in thedirection of said distal end.
 27. The syringe assembly of claim 24wherein said locking element includes one or more proximally extendingbarbs engaging said inside surface of said syringe barrel, and saidlocking element and stopper are positioned such that said plunger rodcan be moved proximally with respect to said locking element.
 28. Amethod for performing a two stroke injection procedure, comprising:providing a syringe comprising a syringe barrel having an inside surfacedefining a chamber, an open end, a distal end and an annular ring; aplunger rod extending within the syringe barrel, the plunger rodincluding an elongate body portion defining a longitudinal axis, astopper at a distal end of the elongate body portion, a disc, and anaxially extending recess formed by a pair of surfaces radially displacedfrom the longitudinal axis of the elongate body portion, the surfacesdefining at least one proximal tooth and at least one distal tooth; anda locking element slidably positioned within the recess and abutting thedisc; performing a first retraction stroke by proximally withdrawing theplunger rod so that the stopper abuts the annular ring, wherein thelocking element remains substantially motionless allowing the proximaltooth to pass under the locking element; performing a first injectionstroke by distally moving the plunger rod so that the stopper abuts thedistal end of the barrel and the proximal tooth abuts the lockingelement, wherein the locking element remains substantially motionlessduring the first injection stroke; performing a second retraction strokeby proximally withdrawing the plunger rod so that the stopper abuts theannular ring, wherein the locking element remains substantiallymotionless allowing the distal tooth to pass under the locking elementso that the locking element abuts the distal tooth; performing a secondinjection stroke by distally moving the plunger rod so that the stopperabuts the distal end of the barrel, wherein the locking element movesdistally with the plunger rod; and locking the plunger rod viaengagement of the locking element with the barrel and stopper renderingthe syringe assembly permanently disabled.